Weird XCode 7 Interface Builder warnings - macos

Question

I have set font traits (bold, light) for several of my labels in an OSX app and now I get these warnings:
.../MainMenu.xib:9:
Xcode.IDEInterfaceBuilder.Cocoa.NSObject.BroadSystemFontWeights
without any explanation. Often the meant label isn't even selected when I click on the warnings. Can someone shed a light on what those warnings mean and how to get rid of them?

Answer 1

This is a warning shown starting from Xcode 7 when UI elements like a label or table view column header use a font style or variation that is not available on older OSes (and of course your project is still targeting them).
In my project a table view column header was using the system font with the "medium" font style variation instead of regular, in a project targeting OS X 10.9+.
The weird thing is I had to restart Xcode as Interface Builder refused to change the style of the control. Possibly a small glitch of this early 7.0.1 Xcode version.

Answer 2

Current answer almost gets it, but problem is not with font styles being unavailable in older targets, it's with Xcode not handling them properly, see full blog post for details.
If you want to keep your styles, use custom textfield with custom inspectable property. Open up identity inspector and set custom class to TextField, preferred font weight attribute will show up in attribute inspector, set the required value, build and enjoy the result.
import AppKit
#IBDesignable public class TextField: NSTextField
{
#IBInspectable public var preferredFontWeight: Int = 0
override public func awakeFromNib() {
if #available(OSX 10.11, *) {
return
}
guard
let weight: Int = self.preferredFontWeight where weight > 0,
let font: NSFont = self.font,
let name: String = font.familyName,
let manager: NSFontManager = NSFontManager.sharedFontManager() else {
return
}
// Full details here – https://developer.apple.com/library/mac/documentation/Cocoa/Reference/ApplicationKit/Classes/NSFontManager_Class/#//apple_ref/occ/instm/NSFontManager/convertWeight:ofFont:
//
// 1 – ultralight
// 2 – thin
// 3 – light, extralight
// 4 – book
// 5 – regular, display
// 6 – medium
// 7 – demi, demibold
// 8 – semi, semibold
// 9 – bold
// 10 – extra, extrabold
// 11 – heavy
// 12 – black
// 13 – ultrablack
// 14 – extrablack
if let font: NSFont = manager.fontWithFamily(name, traits: manager.traitsOfFont(font), weight: weight, size: font.pointSize) {
self.font = font
}
}
}
If you don't really care about the styles, use regular weight font for all text, it should solve the problem, see my earlier answer for available options.